Expansible bit



J. CRAWFORD ANDF. A. WEAVER.

EXPANSIBLE BIT. APPLICATION FILED MAY 12, I920.

1 ,41 5 ,3 1 '7 Patented May 9, 1922.

3 SHEETS-SHEET I.

rfofizv Crawford m a 6 V 6' a Ania/714236 1. CRAWFORD AND F. A. WEAVER.

EXPANSIBLE BIT. APPLICATION HLED MAY 12. I920.

6M0 MAMA/J Patented May 9, 1922.

3YSHEETSSHEET 2.

J. CRAWFORD AND F. A. WEAVER.

EXPANSIBLE BIT.

APPLICATION FILED MAYIZ, 1920.

1,415,317. Patented May 9,1922.

3 SHEETS-SHEET 3.

4 Swvavptow Jam Czam/qrd J'redeI MA. Weaver wire sr JOHN CRAVIFORD AND FREDERICK A. WEAVER, OF DENVER, COLORADO.

EXPANSIBLE BIT.

Application filed May 12, 1920. Serial No. 380,8?5.

Z '0 all whom it may concern:

Be it known that Jor-IN CRAWFORD and FREDERICK A. VVnAvcn, citizens of the United States, residing at Denver, in the county'of Denver and State of Colorado, have invented certain new and useful Improvements in EX- pansible Bits; and they do hereby declare the following to be a full, clear, and exact description of the invention, such as will enableothers skilled in the art to. which it appertains to make and use the same.

This invention relates to tools, and more particularly to eXpansible bits.

It is one of the objects of the present invention to provide an expansible bit in which there may be provided one or more trans-- versely adjustable cutter bladeswhich are arranged in the end face of the head of the bit in such manner that the cutter or cutters are more firmly'supported' and may be read ily removed, replaced and adjusted to the desired projecting distance, and it is a further object of the invention to provide an improvement in expansible bits in which the removable cutters do all the cutting and the work is divided equally during the rotation of the bit into shavings or chips extending from the lead screw to the circumferenceot the bit proportionately to the number of cutters which may be employed.

Another object of the invention is to provide, in an expansible bit, a construction which will make possible and practicable the use of cutters which are broad from cutting edge to back but yet comparatively thin, so as to afford great rigidity in the cutter proportional to the amount of steel required.

It is another Object of the invention to provide a multiple cutter, expansible bit in) which it is necessary to adjust only one of the expansion cutters at an exact position as determined by the diameter of the hole to be bored, and thus enabling the indifferent radial adjustment of the remaining cutters after the position of one of the cutters has beendetermined as required;

It is another object of the present invention to provide a multiple cutter expansible bit in which the cutters are disposed in symmetrical position with relation to the lead screw of the bit sothat cutters operate from the lead screw to the circumference, so that all the cutting is done by the removable, adjustable cutters, which may be readily sharpened out of the tool and in one operation.

Specification of Letters Patent.

Patented May 9, 19225.

itis an important object of the present invention to provide an eXpansible bit of such construction that a minimum number 01'? relat vely separable parts is required; and, in this manner to provide a bit of simple construction and in which the entire cutting edge is on the removable cutters. I

With these and other objects in view the present invention consists in a bit having a head, thetransverse end face of which is provided with means for receiving one or more transversely adjustable and'removable cutters, and in which means are provided for secur ng the'cutters in relatively adjusted position firmly and accurately.

There is described in the following specification and illustrated in the accompanying drawing several bits in which the invention is embodied in various forms, and in which drawing:

Figure 1 is a side elevation of a form of the bit showing a pairo1 symmetrically disposed removable cutters, the shank of the bit being broken away. I

Figure 2 is an underneath plan view of Figure 1.

Figure 3 is a side elevation of the bit shown in Figure 2 looking toward the right hand side of the latter.

Figure 1 is a cross section on line 4-4 of Figure 1.

Figure 5 is an underneath plan view of one of the detached cutters.

Figuretl is an end view of Figure 5 from the right hand end, and

Figure 7 is a transverse section on line- 7-7 of Figure 5.

Sheet 2.

Figure 8 is a side elevation of the invention as embodied in a bit having triple cutting blades.

Figure 9 is abottomplan view of Figure 8.

Figure 10 is a side elevation of Figure 8 looking toward the right side thereof.

F igure ll is across section on line 11-11 of Figure 8.

Sheet 3.

Figure 12 i a side elevation of a bit showing a single cutting blade and in which the head of the bit is arranged to side of the axis oi the lead screw and shank of the bit, the latter being'broken away.

Figure 18 is a side elevation of the bit shown in Figure 12, and

r 1, 3 and Figure 1d isa bottom plan view of Fig ure 12.

Referring to the drawingsthe shank 2 of the tool is provided with an enlarged head having a flat transverse end. and a lead screw 7 extending therefrom. In the flat end of said head is provided one or more transverse cutter receiving slots 5, which may be and preferably are of dovetailed form and arranged tangentially to lead screw 7. Slots 8 are cut in the head 3 dividing said cutter slots 5 longitudinally and extending upwardly in head a substantial height so that the side walls of said cutter slots may be drawn together as by screws 9 and threaded holes 10 to securely grip the cutters 6. The cutter head 3 may be bellshaped a illustrated'in Figs. 1 and 3 in which event slots 8 will converge toward,

their upper ends or the head may be cylindrical as illustrated in Figs. 12 .and 18, in which event if a plurality of cutters were used, the slots 8 would either converge or be parallel as desired. Further slots D (Figs. l) and G (Figs. 8 and 9) are cut in said head to form in conjunction with the beveled edgeof cutter 6 shaving escapement slots when multiple cutters are used.

The cutters 6 are of a trapezoidal form in cross ection adapted to slide transversely in said dovetail cutter slots 5, and are provided with a cutting edge 6 and at least one cutter in each tool is provided with a cutting lip 6 It will be further noted that the cutters are preferably much broader than they are thick and are adapted to lie with their broad surfaces substantially in the plane of the flat end of the head 3 except for the slight inclination sufficient to drop the cutting edge below the plane of the end. face 3 in order to permit the cutting edge to engage and cut the wood and, likewise to raise the noncutting end of the cutter member above the plane of the end face 3 of the head so that such end will clear the wood. In case of three or more cutters the inclination must also be sufiicient to permit the cutters to overlap, as indicated at Figs. 8, 9 and 10, and to allow, between the cutters at the overlap, clearance for shavings. With this arrangement it will be noted that the cuttingedges will be angularly disposed, as above indicated, relatively to the longitudinal axis of the head and will at the same time liein vertical planes parallel with said axis but angularly disposed relatively to each other. 1

It will be noted that this structure affords the maximum rigidity in the cutters with the minimum oftool steel and further provides a wide thin cutting tool which will tend to shave the wood instead of chipping it a is done by the ordinary extension bit.

In the adjustment of the tool the cutters 6 are arranged in the cutter'slots 5 with their cutter edges 6 extending tangentially from the lead screw 7 to the circumference of the cut. In the multiple cutter forms of this invention the cutter having the lip 6 is the only one requiring nicety of adjustment as the other cutters may be more roughly adjusted to a slightly less radius.

In operation the cutters operate from the lead screw to the circumference, and there are no cutting edges integral with the head of the tool thus greatly Simplifying the.

sharpening of the cutting edges, which are entirely removed with the removable cutters and harpened in one operation.

What we claim is I 1. A bit comprising a head, having a flat end face and aplurality of cutters adjustably mounted in the flat end face of said head, said cutters having their long axes inclined relative to the end face of the head and their cutting edges inclined downward from said face to the outer end of the/cutter.

2. A bit comprising a head, with a fiat end face, a plurality of cutters having their long axes inclined relative to the plane of the end face of the head so that said cutters overlap with their cutting edges inclining downwardly from the end face of the head and means for adjustably securing said cut-- ters in the head.

3. A bit comprising a head having an end face with a lead screw, a plurality of slots disposed tangentially of the lead screw in the end face of said head, said slots lying in planes inclined relative to that of the face of the head and cutters having shanks slidable in said slots, said slots of such angularity and said cutters of such thickness to admit of the overlapping of said cutters when a greater number than two'cutters are used on said head.

4. An expansible bit comprising a shank with a longitudinally split head, the latter having a central lead screw in its face anda transverse seat countersunk in the said face tangentially to the lead screw, an adjustable cutter arranged in the seat with its cutting edge tangential to the screw and its width substantially perpendicular to the axis of the shank, the longitudinal axis of the cutter lying at a slight angle to a plane perpendicular to the axis of the shank, the split of the head bisecting the seat in a line par. allel to its length, and means passing through the opposed sections of the head above the cutter head for closing the seat walls on an inserted cutter. 5

5. An expansible bit comprising a shank with an enlarged head portion having a lead undercut in the end face of the head, one of 1 the side-walls of each of the seats being substantially tangential to the lead screw, said head being longitudinally slitted inwardly from the bottom of each slot in a plane parallel with the length of each slot to form relatively movable jaws on each side of each slot, cutter blades adapted to be inserted in the slots to extend with their cutting edges tangentially to the lead screw and their width lying substantially flat across the end face of the head and the lengths of the cutters being slightly inclined with relation to a plane perpendicular to the axis of the shank, and means passing through coordinate portions of the split head for clamping the same onto said inserted cutters.

6. An expansible bit comprising a shank, and having a head with a substantially plane end face and a lead screw coaxial with the axis and projecting from said face, the end face provided with a plurality of angularly disposed undercut slots with their widths substantially perpendicular to the axis of the lead screw and their lengths arranged secantially across the head, the head being slitted longitudinally inwardly from the bottom of the slots so that the side walls thereof form relatively lateral, movable, clamping jaws, complementary cutters constructed and arranged to be fitted in said slots between the jaws, and to be disposed with their cutting edges tangentially to the lead screw, and their bodies lyin with their widths substantially fiat across the end face, and means for clamping the respective jaws of the head onto an inserted cutter.

7. An expansible bit comprising a shank with a longitudinally split head, the latter having a lead screw in its end face coaxial with the shank and a transverse seat counter-sunk in the said face substantially tangential to the lead screw, the head being longitudinally split between the side walls of said seat whereby to form a pair of relatively movable cutter clamping faces; and an adjustable cutter arranged in the seat with its cutting edge substantially tangential to the screw and its width substantially perpendicular to the axis of the shank, the longitudinal axis of the cutter lying at a slight angle to a plane perpendicular to the axis of the shank, the split of the head dividing the seat lengthwise and means for tending to close the split and for clamping the cutter in the seat.

8. An adjustable bit having a cutter carrying head and a lead screw, a plurality of transversely adjustable cutters having cutting edges extending from the lead screw, said cutting edges angularly disposed relative to the longitudinal axis of the head and at least two of the edges lying in vertical planes which are at an angle to each other.

9. In an adjustable bit having a cutter carrying head and a lead screw a plurality of transversely adjustable cutters having cutting edges extending tangentially from said lead screw, and angularly disposed relatively t0 the longitudinal axis of the head and at least two of the edges lying in vertical planes which are at an angle to each other, said head being slotted adjacent and above said cutters to form therewith shaving escapement channels.

10. In an adjustable bit, a head having a flat end face and a plurality of slots in said end face to accommodate cutters, and channels extending upwardly through said head from adjacent slots to permit the escape of chips.

In testimony whereof they afiix their signatures.

JOHN CRAWFORD. FREDERICK A. WEAVER. 

